The Japanese agriculture minister, Tsutomu Takebe, took up chopsticks yesterday in defence of the country's livestock industry, which has been under attack since Asia's first case of mad cow disease was found last month.

He was one of 100 politicians at a hastily arranged "beef party" designed to reassure the worried public that there is nothing to fear from domestically produced meat, despite reports in the media.

People have begun to shun beef since bovine spongiform encephalopathy was found in a five-year-old Holstein dairy cow in Shiroi, eastern Japan, on September 10.

Thousands of schools have removed beef, and in some cases even milk, from their menus. Restaurants have followed suit and a growing list of Asian countries have banned imports from Japan.

The business daily Nihon Kezai reported that the price beef fell by 20-30% in less than three weeks.

McDonald's and other fast food chains have been hard hit by the BSE panic, but the politicians at yesterday's publicity stunt tucked into more traditional dishes such as sukiyaki and tepanyaki, reflecting the prestigious image of Japanese beef.

Japanese livestock farmers have devoted themselves to producing the world's most succulent meat. Prized cuts of Kobe, Matsuzaka or Miyazaki beef are known as shimofuri , or fallen frost, because of the white flecks of fat that make them so tender.

To achieve this effect, the cows are given treatment that many humans would envy. Farmhands massage them and put beer in their troughs. so that their muscles relax. To avoid stress, which is thought to toughen the meat, some farms keep the cattle in separate sheds.

Japan's cloning programme is dedicated to upgrading the national cattle herd.

Department stores sell prized meat for up to 5,000 yen (£30) a 100g. People have been willing to pay because the quality of domestically produced beef is legendary.

Given this reputation, it has come as a shock to the Japanese public that many livestock farmers have been giving their animals imported meat-and-bone feed, which is widely believed to be the means by which BSE is transmitted.

The government banned imports of British feed in 1996, but did not close the door on imports from other European countries until January, despite warnings from the World Health Organisation about the risk of infection.

In the interim 80,000 tonnes of feed was imported from Europe.

Fear of a cover-up has been raised by the agriculture ministry's initial response to the discovery of BSE in Japan.

A ministry spokesman said the infected cow's carcass had been incinerated, but it has since emerged that the animal was crushed to produce feed for cows and chickens.

The prime minister, Junichiro Koizumi, rapped the ministry's "inappropriate" handling of the case, and before dining yesterday Mr Takebe apologised to parliament.

"I am very sorry that the administrative response to the mad cow disease problem has been grossly insufficient, and I feel keenly responsible," he said.

His ministry has announced a blanket ban on domestic and imported meat-and-bone feed for all animals. Existing supplies will be incinerated, tests will be widened and abattoirs instructed to burn rather than recycle the organs of slaughtered cows.

Consumer groups say that such steps, and yesterday's publicity stunt, are not enough to restore trust.